A known vehicular door operation detecting apparatus is disclosed, for example, in JP2015-21238A which is hereinafter referred to as Reference 1. The vehicular door operation detecting apparatus disclosed in Reference 1 includes a lower capacitance sensor, an upper capacitance sensor and a control portion. The lower capacitance sensor includes at least two sensor portions provided at a vehicle so as to be spaced away from each other and detects the leg (foot) portion of a user (human being). The upper capacitance sensor is provided at an upper side of the lower capacitance sensor to detect the body of the user except for the leg portion thereof. The control portion outputs a drive signal to a drive unit of a vehicle door for driving the vehicle door to open or close in a case where the control portion inputs a detection signal from one of the sensor portions of the lower capacitance sensor and a detection signal from the upper capacitance sensor. The control portion is inhibited from outputting the drive signal to the drive unit in a case where the control portion inputs detection signals from two or more of the sensor portions.
According to the aforementioned construction, possibility of wrong door opening and closing because of a detection of a small animal or an object, for example, by only the lower capacitance sensor may decrease. In addition, safety of the user is secured because the door opening or closing is not started or is stopped in a case where at least the two sensor portions of the lower capacitance sensor detect the user.
According to the vehicular door operation detecting apparatus disclosed in Reference 1, in order to detect an operation of the user related to opening and closing of the door which is hereinafter referred to as an operation of the user relative to the door, even when an engine of the vehicle is stopped, sensing by the capacitance sensor needs to be continued while battery consumption is restrained. Thus, the control portion performs the sensing intermittently (which corresponds to an intermittent sensing mode) in a case where the user is not present around the vehicle (specifically, the capacitance sensor) and performs the sensing continuously (which corresponds to a continuous sensing mode) in a case where the user comes closer to the vehicle, thereby restraining the battery consumption.
In this case, the battery consumption may be reduced by increasing an intermittent time. Nevertheless, the increase of the intermittent time may increase possibility of a delay of detection timing for detecting presence of the user, which may inhibit a prompt detection of the operation of the user relative to the door.
A relationship between the intermittent time and the detection timing for the presence of the user, for example, is explained in detail below. FIGS. 6 and 7 are time charts each of which illustrates changes of a capacitance in a case where the user comes closer to the vehicle and thereafter leaves the vehicle (i.e., capacitance sensor). Detection ability of the capacitance sensor is the same between FIGS. 6 and 7. In FIGS. 6 and 7, each filled circle indicates a sensing time point at which the capacitor sensor performs the sensing. For example, in the intermittent sensing mode, the presence of the user is detected (i.e., determined) when a capacitance Cs exceeds a predetermined detection threshold value Cth at the aforementioned sensing time point.
In FIG. 6, the sensing is performed each detection time (which is a calculation time for a required process, for example) T in the continuous sensing mode while the sensing is performed each intermittent time T_long80 (>1) which is longer than the detection time T in the intermittent sensing mode.
Accordingly, the presence of the user is detected for the first time at the time the capacitance Cs exceeds the detection threshold value Cth at a sensing time point t81 in the intermittent sensing mode. That is, at a sensing time point t80 (=t81−T_long80) immediately before the sensing time point t81, the presence of the user is not detected because though the capacitance Cs approximates the detection threshold value Cth, the capacitance Cs does not yet exceed the detection threshold value Cth. The intermittent sensing mode is switched to the continuous sensing mode at the sensing time point t81 and the sensing is repeatedly performed each detection time T until the operation of the user is detected.
In FIG. 7, the sensing is performed each detection time T in the continuous sensing mode while the sensing is performed each intermittent time T_long 90 (>T_long 80) in the intermittent sensing mode.
Accordingly, the presence of the user is detected for the first time at the time the capacitance Cs exceeds the detection threshold value Cth at a sensing time point t91 in the intermittent sensing mode. That is, at a sensing time point t90 (=t91−T_long90) immediately before the sensing time point t91, the presence of the user is not detected because though the capacitance Cs approximates the detection threshold value Cth, the capacitance Cs does not yet exceed the detection threshold value Cth. The intermittent sensing mode is switched to the continuous sensing mode at the sensing time point t91 and the sensing is repeatedly performed each detection time T until the operation of the user is detected.
As clearly seen from FIGS. 6 and 7, although the changes of the capacitance Cs are the same between FIGS. 6 and 7, the sensing time point t91 at which the sensing mode is switched to the continuous sensing mode as illustrated in FIG. 6 is delayed from the sensing time point t81 at which the sensing mode is switched to the continuous sensing mode as illustrated in FIG. 7. That is, the increase of the intermittent time may cause a delay of a start time of the continuous sensing mode, depending on timing of the sensing. In a case where the start time of the continuous sensing mode is delayed, prompt detection of the user's operation relative to the door may not be detected.
A need thus exists for a vehicular door operation detecting apparatus which is not susceptible to the drawback mentioned above.